Osteoporosis is morbid, mortal, and costly. Approximately 1 in 4 adults who sustain a hip fracture experience a permanent loss of independence and 15-25% die in the subsequent year. Many fractures could be prevented through preventive measures, from better practice of fall reduction strategies to targeted use of effective pharmacotherapy. However, few patients at-risk for fractures from osteoporosis use drugs for osteoporosis persistently. We, and many others, have documented sub-optimal use of these drugs. Several theory-based large-scale public health trials by our group suggest that rates of treatment initiation can be improved through a combined approach targeting both patients and their physicians. We urgently need to develop methods for improving adherence with osteoporosis treatments. To this end, we propose a cluster randomized controlled trial (RCT) to improve adherence with drugs for osteoporosis. This proposal builds on several decades of research by our group to improve medication use and 5 years of focused investigations on improving osteoporosis care. As well, we utilize a long-term collaboration between the Brigham and Women's Hospital (BWH) Division of Pharmacoepidemiology and Pharmacoeconomics and the Pennsylvania Pharmaceutical Assistance Contract for the Elderly (PACE). Aim 1) Conduct a cluster RCT to test patient- and physician-targeted interventions combined with a systems approach to improve adherence with medications for osteoporosis. We will enroll new users of medications for osteoporosis in a three arm RCT - control, patient intervention, and combined patient and physician interventions. The trial will focus on improving the following outcomes: 1) adherence with osteoporosis medications;2) intermediate outcomes hypothesized to mediate the effects of the intervention on adherence (such as resolution of barriers to adherence, patient's osteoporosis knowledge, perceived susceptibility, and self-efficacy);and 3) the rates of fracture. Aim 2) Calculate the cost-effectiveness of the cluster RCT conducted in Aim 1. Using data from the trial conducted in Aim 1, we will calculate the costs and benefits of the intervention and determine the potential cost per fracture averted. Many of the assumptions for this analysis will be derived from Aim 1, and several regarding the effectiveness of drugs in reducing fractures will be literature-based. Appropriate sensitivity analyses will allow for estimation of cost and benefits under a variety of scenarios. Lay Language: Osteoporosis is morbid, mortal, and costly. Effective treatments are not used persistently by patients. We will test an intervention to improve medication adherence in a large group of at-risk older adults. The economic implications of the intervention will also be analyzed.